Extramedullary Plasmocytoma

Extramedullary plasmocytoma is a tumor chiefly located in the upper air passages and oral cavity, usually characterized by a slow rate of growth and lack of the biochemical data distinctive of multiple myeloma. Eight cases of extramedullar plasmocytoma are reported, six located in the nasal cavity, one in the maxillary sinus and one in the oropharynx, and the relevant histological features are described: the pyronin affinity of cells, more evident at pH 4.8, was constantly positive; the Russell bodies and the Mott cells, similar to those seen in plasmacell granulomas, were seldom present; the argyrophylic reticulum was rather regular and generally with alveolar pattern; the stainability with the amyloid technique was positive in three cases. Such results are discussed in comparison with reports of other authors. The pertinent literature concerning clinical and pathological data is briefly reviewed. On the basis of the most recent studies on plasmacells, the histogenesis of extramedullary plasmocytoma is discussed, particularly in respect to plasmacell granulomas and multiple myeloma; the possibility that the basic cells constituting such tumors could be related to proplasmocyte is then suggested.